Sealed ball bearing

ABSTRACT

It is an object of the invention to provide a seal-type rolling bearing which not only can secure a high seal sealing property but also can equalize the internal pressure of the bearing equal to the external pressure thereof.  
     In the invention, in the case of a contact seal ( 8   a ) disposed on the water-drenchable side of a seal-type rolling bearing ( 1 ), there is formed no air hole in the lip ( 10 ) thereof and, in the case of a contact seal ( 8   b ) on the counter-water-drenchable side, there is formed an air hole ( 12 ) in the leading end ( 11 ) of the lip ( 10 ) thereof.

TECHNICAL FIELD

The present invention relates to a sealed-type rolling bearing includingtwo contact-type seal plates on the two right and left sides thereofbetween an inner ring and an outer ring.

BACKGROUND ART

Conventionally, in a vehicle such as a car, in a seal-type rollingbearing for use in a power transmission pulley, an electromagneticclutch or the like used to transmit power to a compressor included in arefrigeration cycle, there are disposed a total of two contact seals(seal plates) one on either side thereof to thereby attain a sealedcondition.

In each of the seal lips of the two-side seal plates, there is formed anair hole (or a slit) in at least one portion thereof in thecircumferential direction thereof.

The reason for this is as follows: that is, in case where a contact sealbearing without air hole is incorporated, when the pressure of theinterior of the bearing rises and lowers, the internal and externalpressures of the bearing cannot be equalized, which incurs a fear thatthere can occur seal removal, seal lip adsorption phenomenon or thelike; and, therefore, there is proposed a bearing in which, by escapingthe air through the air hole to thereby equalize the pressure of theinterior of the bearing with the pressure of the exterior thereof, theabove-mentioned seal removal, seal lip adsorption phenomenon or the likecan be prevented (for example, JP-UM-B-6-50655, JP-UM-A-6-73454, and thelike).

However, in the conventional contact seal (seal plate) bearing having anair hole, when the bearing at a high temperature is drenched with waterdrawn in from outside and is thereby cooled suddenly (for example, whena vehicle passes through a puddle of water while it is running), thepressure of the interior of the bearing is lowered suddenly, so that, atthe same time when the air is drawn in through the air hole, the waterexisting outside is also sucked in through the air hole, which reducesthe life of the bearing outstandingly.

The present invention at eliminating the above-mentioned drawbacks foundin the conventional bearings. Accordingly, it is an object of theinvention to provide a seal-type rolling bearing which not only cansecure a high seal sealing performance but also can equalize thepressure of the interior of the bearing with the pressure of theexterior thereof.

DISCLOSURE OF THE INVENTION

Technical means provided by the invention in attaining the above objectis a bearing for incorporation into a power transmission pulley or anelectromagnetic clutch, wherein, between an inner ring and an outerring, there are interposed two contact-type seal plates respectively onthe counter-water-drenchable side and water-drenchable side thereof, onthe counter-water-drenchable side, there is disposed the seal platehaving an air hole formed in the leading end of a lip thereof forcontrolling the pressures of the interior and exterior of the bearing,and, on the water-drenchable side, there is disposed the seal platewithout air hole.

Also, in a rolling bearing including two contact-type seal platesrespectively on the two right and left sides thereof between an innerring and an outer ring, only the contact-type seal plate on one sidethereof includes, in the lip leading end thereof, an air hole forcontrolling the pressures of the interior and exterior of the bearing,and, according to the using conditions, the provision directions of thecontact seal including an air hole and the seal on the opposite side canbe optimized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially longitudinal section view of an embodiment of aseal-type rolling bearing according to the invention;

FIG. 2 is an enlarged longitudinal section view of the seal plateportion on the counter-water-drenchable side of the embodiment shown inFIG. 1;

FIG. 3 is an enlarged longitudinal section view of the seal plateportion on the water-drenchable side of the embodiment shown in FIG. 1;

FIG. 4 shows a concrete embodiment and is a partially longitudinalsection view of a power transmission pulley and a seal-type rollingbearing according to the invention, showing a state in which the latteris incorporated into the former;

FIG. 5 shows a second concrete embodiment and is a partiallylongitudinal section view of an electromagnetic clutch and a seal-typerolling bearing according to the invention, showing a state in which thelatter is incorporated into the former;

FIG. 6 is a view of the results of a bearing water pouring test; and,

FIG. 7 is a view of the results of a seal lip adsorption test (bearingstart torque).

By the way, referring to the reference characters used in the drawings,1 designates a seal-type rolling bearing, 2 an inner ring, 4 an outerring, 8 a a water-drenchable-side seal plate, 8 b acounter-water-drenchable-side seal plate, 10 a lip, 12 an air hole, 14 apower transmission pulley, and 17 an electromagnetic clutch,respectively.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, description will be given below of an embodiment of a seal-typerolling bearing according to the invention.

In the present embodiment, there is typically disclosed a double-rowangular ball bearing for describing an embodiment of a seal-type rollingbearing according to the invention. However, the double-row angular ballbearing is not limitative but it can also be changed properly to otherbearing such as a combined angular ball bearing without departing fromthe scope of the invention.

FIG. 1 is a partially longitudinal section view of a seal-type rollingbearing 1 according to the present embodiment; and, the bearing 1comprises an inner ring 2, an outer ring 4, a rolling body 6, a retainer7, and two seal plates 8.

By the way, in the case of the inner ring 2, outer ring 4, a rollingbody 6 and retainer 7, their structures are not limited to thoseemployed in the present embodiment, but conventionally known structurescan also be applied thereto within the scope of the invention. Thus, thedetailed description thereof is omitted here.

Each of the seal plates 8 is formed as a disk-shaped body as a wholemade of elastic material such as rubber or synthetic resin, while theseal plate 8 is disposed in such a manner that its outside diameter 9side is fixed to a peripheral groove 5 formed in the inside diametersurface of the outer ring by calking or by similar means and itsinside-diameter-side lip 10 is contacted with a peripheral groove formedin the outside diameter surface of the inner ring; and, the two sealplates 8 are interposed between the inner and outer rings 2, 4respectively on the two right and left sides of the bearing. And, an airhole 12 is formed only on the leading end (end face) 11 side of the lip10 of the counter-water-drenchable-side seal plate (contact seal) 8 b,whereas no air hole is formed in the lip 10 of the water-drenchable-sideseal plate (contact seal) 8 a.

The air hole 12 is formed in the leading end (end face) 1 of the lip 10in contact with a peripheral-groove wall surface 3 a formed in the innerring outside-diameter surface in such a manner that it penetratesthrough the lip 10 leading end face in the diameter direction thereof.

In the case of the air hole 12, one or more air holes 12 are formed atintervals. In case where two or more air holes 12 are formed, thepositions of the air holes 12—may be the same in the peripheraldirection of the lip 10 or may be shifted from each other; and, theintervals between the air holes 12—may be the same or may be different.That is, the positions and intervals of the air holes 12 can be selectedarbitrarily within the scope of the invention.

Also, the air holes 12 may also be composed of continuous grooves whichare formed in the end face 11 of the lip 10 in contact with the wallsurface 3 a so as to communicate with each other in the diameterdirection of the end face 1 (not shown) In this case as well, there canbe obtained similar operation and effects to the previously describedair hole.

In this case, the diameter and the number of grooves can be selectedarbitrarily as well as the shape of grooves is not limited to a straightshape but can be selected arbitrarily.

The contact seal 8 according to the present embodiment includes a coremetal 13. However, the shape of the core metal 13 is not limited to aspecific shape. Also, there may also be used a contact seal which doesnot include a core metal.

Further, the shape of the lip 10 is not limited to the illustrated shapeat all, but any other shape can also be used arbitrarily within thescope of the invention, provided that it has a known structure includingthe end face 11 to be contacted with the peripheral groove 3. That is,except for a structure in which the air hole 12 is formed in the lip 10,any one of the known structures may be applied as the whole structure ofthe seal plate 8.

Therefore, since the counter-water-drenchable-side contact seal 8 bincludes the air hole 12 on the leading end (end face) 11 side of thelip 10 and thus, even in case where the internal pressure of the bearingis lowered due to the sudden cooling of the bearing, the external andinternal pressures of the bearing can be equalized with each other,there is no possibility that adsorption can occur in the seal lip 10. Onthe other hand, in the case of the water-drenchable-side contact seal 8a, because no air hole 12 is formed in the lip 10 thereof, even in casewhere the bearing is cooled suddenly because it is drenched to thewater, there is no possibility that the water can be drawn in fromoutside.

Now, FIG. 6 shows the results of a bearing water pouring test.

[Test Conditions]

Bearing temperature: water is poured after bearing is held attemperature of 120° C. for 1 h.

Number of revolutions: 1600 rpm

Quantity of water poured: 540 cc/min

Time: 10 min.

The test results show that the bearing 1 according to the presentembodiment, in which the water-pouring-side (the water-drenchable-side)contact seal 8 a has no air hole and the counter-water-pouring-side (thecounter-water-drenchable-side) contact seal 8 b has an air hole 12, ismore excellent in the sealing performance than a comparison bearing inwhich each of the two side contact seals has an air hole.

Also, FIG. 7 shows the results of a seal lip adsorption test.

In the present test, after the bearing according to the presentembodiment and two comparison embodiments are previously held under thecondition of 120° C.×1 h and are then left at a desired temperature,start torques due to the adsorption of the seal lips were measured.

The adsorption test results show the following fact: that is, in thecase of a comparison embodiment in which no air hole is formed in thetwo side contact seals thereof, there is found an increase in the starttorque due to the adsorption of the lips at any one of temperatures inthe range −30° C.˜8° C.; and, in the bearing 1 according to the presentembodiment in which the water-pouring-side (the water-drenchable-side)contact seal 8 a has no air hole and the counter-water-pouring-side (thewater-drenchable-side) contact seal 8 b has the air hole 12, there isfound no adsorption and thus the internal and external pressures of thebearing are kept equalized to each other.

Embodiments

[First Embodiment]

Now, with reference to FIG. 4, description will be given below of aconcrete embodiment in which the seal-type rolling bearing 1 accordingto the invention is incorporated into a power transmission pulley 14. Bythe way, FIG. 4 shows an example of a power transmission pulley intowhich a seal-type rolling bearing according to the invention can beincorporated, and thus the invention is not limited to this at all.Also, the present embodiment shows an embodiment in which a double-rowangular ball bearing is incorporated but a seal-type rolling bearing tobe incorporated into a power transmission pulley is not limited to thisat all.

In FIG. 4, reference character 1 designates a seal-type rolling bearingaccording to the present embodiment, 15 stands for a pulley, and 16represents a compressor housing.

In the case of the power transmission pulley 14 which is used totransmit power to a compressor in a refrigerating cycle for a vehiclesuch as a car, due to the structure thereof, the compressor andcounter-compressor sides thereof are greatly different in theeasy-to-be-drenched-with-water property from each other.

That is, on the compressor side (water-drenchable side), since it can beeasily drenched with water when the water is drawn in from outside,there is disposed a contact seal 8 a in which no air hole is formed inthe lip 10 thereof; and, on the other hand, on the counter-compressorside (counter-water-drenchable side), because it is hard to be drenchedwith water, there is disposed a contact seal 8 b in which an air hole isformed in the lip thereof.

When the hot-temperature bearing is cooled down suddenly due to thewater drawn in from outside, for example, when the vehicle passesthrough a puddle while it is running, the internal pressure of thebearing is caused to lower down suddenly. However, as in the presentembodiment, in case where the seal-type rolling bearing 1 according tothe invention is incorporated into the power transmission pulley 14 ofthe vehicle, since the air hole 12 exists in the lip 10 of thecounter-water-drenchable-side contact seal 8 b, the outside air is drawnin to thereby be able to equalize the internal and external pressures ofthe bearing uniform with each other. Also, because no air hole ispresent in the lip 10 of the water-drenchable-side contact seat 8 a,there is no possibility that the outside water can be drawn in.

[Second Embodiment]

Now, with reference to FIG. 5, description will be given below of asecond concrete embodiment in which the seal-type rolling bearing 1according to the invention is incorporated into an electro-magneticclutch 17. By the way, in the present embodiment, there is shown a casein which a double-row angular ball bearing is incorporated; however, aseal-type rolling bearing to be incorporated into an electromagneticclutch is not limited to this at all.

In FIG. 5, reference character 1 designates a seal-type rolling bearingshown in the present embodiment, 18 an electromagnetic coil, 19 acompressor housing, and 20 a long labyrinth, respectively.

In the case of the electromagnetic coil 18 which is used to transmit therotation power of an engine for running a vehicle such as a car to acompressor in a refrigerating cycle for the vehicle intermittently,since the compressor side thereof is hard to be drenched with water dueto the structure thereof, there is disposed a contact seal 8 b with anair hole 12 formed in the lip 10 thereof; and, on the other hand, thecounter-compressor side thereof is easy to be drenched with water whenthe water is drawn in from outside, there is disposed a contact seal 8 awith no air hole formed in the lip 10 thereof.

When the hot-temperature bearing is suddenly cooled because it isdrenched with water drawn in from outside, for example, when the vehiclepasses through a puddle while running, the pressure of the interior ofthe bearing is lowered down suddenly. However, as in the presentembodiment, in case where the seal-type rolling bearing 1 according tothe invention is incorporated into the electromagnetic clutch 17, sincethe air hole 12 is present in the lip 10 of a contact seal 8 b disposedon the counter-water-drenchable side of the bearing, the outside air canbe drawn in to thereby be able to equalize the internal and externalpressures of the bearing equal to each other. Also, because no air holeis present in the lip 10 of a contact seal 8 a disposed on thewater-drenchable side, there is no possibility that water can be drawnin from outside.

Although the invention has been described in detail and also withreference to the specific embodiments heretofore, it is obvious to aperson skilled in the art that various changes and modifications arealso possible without departing from the spirit and scope of theinvention.

The present application is made based on the Japanese Patent Application(JP-Application 2001-348043) filed on Nov. 13, 2001 and the contentsthereof are incorporated into the present application for reference.

INDUSTRIAL APPLICABILITY

Since the invention is structured in the above-mentioned manner, it canprovide a seal-type rolling bearing which not only can secure a highseal sealing property but also can equalize the internal pressure of thebearing equal to the external pressure thereof. That is, a contact sealhaving an air hole is disposed on the side of the bearing that is hardto be drenched with water and a perfectly sealing contact seal withoutair seal is disposed on the side thereof that is easy to be drenchedwith water. Thanks to this, when the bearing held at a high temperatureis drenched with water drawn in from outside and is thereby cooled downsuddenly, not only the water can be prevented from being drawn inthrough the air hole excessively, but also the presence of the air holein the opposite-side seal lip can prevent seal lip adsorption, sealremoval and other problems which are possibly caused by a decrease or anincrease in the pressure of the interior of the bearing.

1. A seal-type rolling bearing incorporated into a power transmissionpulley or an electromagnetic clutch, wherein, between an inner ring andan outer ring, contact-type seal plates are respectively interposed onthe counter-water-drenchable side and on the water-drenchable sidethereof, on the counter-water-drenchable side, a seal plate including,in the lip leading end portion thereof, an air hole for controlling theinternal and external pressures of the bearing is disposed, and, on thewater-drenchable side, a seal plate without air hole is disposed.